Get Current Logged in Customer Info

Check if the customer is logged in then

Mage::getSingleton('customer/session')->isLoggedIn();

Get Current Customer Name

Mage::getSingleton('customer/session')->getCustomer()->getName();

You can Get Current Customer All Information

echo "<pre>"; print_r(Mage::helper('customer')->getCustomer()->getData()); echo "</pre>";

Ger Current Logged in Admin

Mage::getSingleton('admin/session')->getUser();